Erwin Rohde (1845-1898), Psyche: The Cult of Souls and Belief in Immortality among the Ancient Greeks, tr. W.B. Hillis (London: Routledge & Kegan Paul, 1925; rpt. Chicago: Ares Publishers, Inc., 1987), Appendix VII, pp. 593-595, discusses three categories of those who wander after death: those who died untimely (ἄωροι), those who died violently (βιαιοθάνατοι, usually suicides), and those who weren't buried (ἄταφοι). See also Robert Garland, The Greek Way of Death (Ithaca: Cornell University Press, 1985), pp. 77-88 (ἄωροι), 95-99 (βιαιοθάνατοι), and 101-103 (ἄταφοι).

Ah dear husband,
you wander in death
unburied and with no lustral water...

ὦ φίλος ὦ πόσι μοι,
σὺ μὲν φθίμενος ἀλαίνεις
ἄθαπτος ἄνυδρος...

At Euripides, Suppliant Women 62, Gottfried Hermann conjectured σώματ᾽ ἀλαίνοντα τάφου. He explained the genitive τάφου by claiming that the verb ἀλαίνω could imply a lack, and by comparing ἀλάομαι ("wander, roam"), which can (with a genitive) have the additional meaning "wander away from, miss a thing."